It really depends on what you consider cheap. Your best bet would be to try to find a sublet. You might be able to get something in Manhattan if your friends are willing to pay 500+ each a month and with that, at least 3 of you are going to wind up sleeping on the floor.
Take a look at sublet.com, you can search through summer rentals in all the boroughs and you'll probably find something you can manage.
If not in Manhattan try Jersey City, Hoboken, Long Island City, Astoria, Sunnyside, Williamsburg, and Greenpoint. all these areas are relatively close to Manhattan (you can walk into Manhattan across the Queensborough Bridge from Long Island City) and have easy access to public transportation.
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